Direct expansion cooler high velocity dished head

ABSTRACT

A dished head header assembly for a heat exchanger having a containment body that includes a rounded, or dished, wall portion forming an interior cavity. A flange attaches to the containment body and fastens the header assembly to the heat exchanger. A plurality of refrigerant passageways are extended through an opening in the containment body into the interior cavity. At least one baffle is attached to the rounded wall portion. The baffle divides the interior cavity into a plurality of sub-cavities. At least one divider divides the sub-cavities into a plurality of chambers. The plurality of passageways includes an inlet connection and an outlet connection for a plurality of refrigerant circuits. Each passageway is disposed in a corresponding chamber of the plurality of chambers. Extensions into the headers with diffusers insure efficient operation and performance of the heat exchanger. The adjustable flow restrictor plate maintains optimum velocities to further enhance performance.

FIELD OF THE INVENTION

The present invention is directed to shell and tube heat exchangers. Inparticular, the present invention is directed to headers for shell andtube heat exchangers used with heating ventilation and air conditioning(HVAC) systems.

BACKGROUND OF THE INVENTION

Shell and tube heat exchangers typically include headers on each end ofthe shell in order to provide access to the tubes within the shell forcleaning or service. The headers also provide containment forrefrigerant or heat exchange fluid and provide the refrigerant or heatexchange fluid to the tubes. Chillers systems typically include achiller heat exchanger, which is a shell and tube heat exchanger havinga refrigerant flow in the tubes and heat exchange fluid, such as water,flowing in the shell. Each end of the chiller heat exchanger includes aheader fastened to the shell. The header includes a flat head plate anda baffle chamber. The head plate is a flat, thick plate that providescontainment of the refrigerant within the system. A gasket is placedbetween the head plate and the baffle chamber in order to reduceleakage. The baffle chamber contains one or more baffles to direct theflow of refrigerant into the tubes of the shell. The baffles alsosubstantially prevent leakage between the inlet and outlet. A secondgasket is placed between the baffle chamber and the shell in order toreduce leakage. Chiller systems may also include multiple refrigerantcircuits having refrigerant loops that are independent of each other. Insystems having multiple circuits, a divider between the circuits mustalso be included in the baffle chamber and independently attached. Thedivider requires bolts that fasten the divider to the end of the shell,adding to the complexity of installation, requiring additional gaskets,reducing the area available for tubes within the shell, and causingadditional stress on the bolts fastening the header to the shell. Thesechiller heat exchangers have the additional drawback that multiplegaskets are required, increasing the occurrence leakage of refrigerantincreasing the service costs. These chiller heat exchangers have thefurther drawback that the flat plate on the header is relatively thickand heavy increasing material cost and weight of the system. Additionalbolts positioned at the center of the flat head, referred to as centerbolts, are required on the flat heads to try to minimize deflection andavoid excessively thick heads. However, these center bolts are generallyoverstressed and create additional leakage paths and cost.

Therefore, what is needed is a header assembly that containsrefrigerant, requires simpler gasketing, weighs less, costs less,provides reduced stress for the fasteners attaching the head to the heatexchanger, provides high velocity refrigerant, and high efficiencyoperation, and eliminates the center bolts.

SUMMARY OF THE INVENTION

The present invention includes a dished-head header assembly for a heatexchanger having a containment body. The containment body includes arounded, or dished, wall portion forming an interior cavity. A flangeattaches to the containment body and fastens the header assembly to theheat exchanger. A plurality of refrigerant passageways are extendedthrough an opening in the containment body into the interior cavity. Atleast one baffle is attached to the rounded wall portion. The baffledivides the interior cavity into a plurality of sub-cavities. At leastone divider divides the sub-cavities into a plurality of chambers. Theplurality of passageways includes an inlet connection and an outletconnection for a plurality of refrigerant circuits. Each passageway isdisposed in a corresponding chamber of the plurality of chambers.Extensions into the headers with diffusers insure efficient operationand performance of the heat exchanger. The adjustable flow restrictorplate maintains optimum velocities to further enhance performance.

The present invention also includes another embodiment including aheader assembly for a heat exchanger having a containment body havingreturn chambers. The containment body includes a rounded wall portionforming an interior cavity. A flange attaches to the containment bodyand fastens the header assembly to the heat exchanger. A gasket sealsthe chambers of the containment body against the heat exchanger in orderto substantially prevent leaks of refrigerant to the atmosphere andbetween the plurality of chambers when the header assembly is attachedto the heat exchanger. At least one divider divides the cavity into aplurality of chambers. The plurality of chambers includes a returnchamber for each refrigerant circuit.

The present invention also includes a heat exchanger, including chillerheat exchangers. The heater exchanger includes a shell for containingheat transfer fluid having a first end and a second end. A plurality oftubes for containing refrigerant are arranged and disposed within theshell. The plurality of tubes includes a first set of tubes and a secondset of tubes. A first header assembly is detachably fastened to thefirst end and includes a first containment body. The first containmentbody includes a rounded wall portion forming an interior cavity. Aflange attaches to the containment body and fastens the header assemblyto the heat exchanger. A plurality of refrigerant passageways areextended through an opening in the first containment body into theinterior cavity. At least one baffle is attached to the rounded wallportion. The baffle divides the interior cavity into a plurality ofsub-cavities. At least one divider divides the sub-cavities into aplurality of chambers. The plurality of passageways includes an inletconnection and an outlet connection for a plurality of refrigerantcircuits. Each passageway is disposed in a corresponding chamber of theplurality of chambers.

A first gasket is disposed between the first header and the first end tosubstantially prevent leakage of refrigerant from the first headerassembly. A second header assembly is detachably fastened to the secondend of the shell. The second header assembly includes a secondcontainment body having return chambers. The second containment bodyincludes a rounded wall portion forming an interior cavity. A flangeattaches to the second containment body and fastens the header assemblyto the heat exchanger. A gasket seals the chambers of the secondcontainment body against the heat exchanger in order to substantiallyprevent leaks of refrigerant to the atmosphere and between the pluralityof chambers when the header assembly is attached to the heat exchanger.At least one divider divides the cavity into a plurality of chambers.The plurality of chambers includes a return chamber for each refrigerantcircuit. A second gasket is disposed between the second header and thesecond end substantially preventing leakage of refrigerant from thesecond header assembly.

One advantage of the present invention is that the rounded headergeometry provides containment of the refrigerant with less material,stronger attachment to the flange and variable chamber sizes via flowrestrictor plates to maintain high refrigerant velocities and highoperating efficiency.

Another advantage of the present invention is that Another advantage ofthe present invention is that the header assembly only requires a singlegasket between the shell and the header. The reduction in the number ofgaskets provides a more reliable seal that has reduced leaks and reducedservice costs.

Another advantage of the present invention is the lack of center boltsattaching the header to the shell. Center bolts are not required becauseof the inherent strength efficiency of the rounded/dished heads. Theremoval of the need for center bolts provides a seal that is easier tomaintain, provides less stress on the bolts of the flange and provides agreater amount of area in which tubes for heat exchange may beinstalled.

Another advantage of the present invention is the attachment of thebaffles to the header, providing a single piece for installation.Utilizing a single piece header allows for installation that is simplerand less susceptible to leakage.

Another advantage of the present invention is that the inlet piping isattached to the header and extended into the inlet and outlet chambersfor more direct flow, increasing the velocity of the refrigerant andefficiency of the operation of the heat exchanger. In addition, theextended nozzles are easier and less costly to fabricate. Diffusers atthe end of the extended nozzles facilitate efficient operation andimprove performance.

Another advantage of the present invention is that the baffles may bearranged in a plurality of configurations, which can adjust the size ofthe chambers within the head. Adjustment of the chamber size providescontrol of the velocity of the refrigerant and residence time of therefrigerant in the header. The control of the velocity and residencetime allows the header to be customized to the particular applicationand/or retrofitted to existing heat exchangers.

Other features and advantages of the present invention will be apparentfrom the following more detailed description of the preferredembodiment, taken in conjunction with the accompanying drawings whichillustrate, by way of example, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side view of a known chiller heat exchanger.

FIG. 2 shows a side view of a chiller heat exchanger according to thepresent invention.

FIG. 3 shows a cutaway view of a chiller heat exchanger according to oneembodiment of the present invention.

FIG. 4A shows a cutaway side view of an inlet/outlet header according toone embodiment of the present invention.

FIG. 4B shows a cutaway front view of an inlet/outlet header accordingto one embodiment of the present invention.

FIG. 5A shows a cutaway side view of a return header according to oneembodiment of the present invention.

FIG. 5B shows a cutaway front view of a return header according to oneembodiment of the present invention.

FIG. 6 shows a perspective view of an inlet/outlet header according toone embodiment of the present invention.

FIG. 7 shows a perspective view of a return header according to oneembodiment of the present invention.

FIG. 8A shows a cutaway side view of an inlet/outlet header according toan alternate embodiment of the present invention.

FIG. 8B shows a cutaway front view of an inlet/outlet header accordingto an alternate embodiment of the present invention.

FIG. 9A shows a cutaway side view of a return header according to analternate embodiment of the present invention.

FIG. 9B shows a cutaway front view of a return header according to analternate embodiment of the present invention.

FIG. 10 shows a perspective view of an inlet/outlet header according toan alternate embodiment of the present invention.

FIG. 11 shows a perspective view of a return header according to analternate embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

HVAC systems may include refrigerant circuits having a compressor, acondenser, and an evaporator connected in a refrigerant loop.Refrigerant is circulated through the refrigerant loop to the variouscomponents. The compressor compresses refrigerant vapor and delivers itto the condenser. The refrigerant vapor delivered by the compressor tothe condenser enters into a heat exchange relationship with water orother suitable heat exchange fluid, heating the water while undergoing aphase change to a refrigerant liquid as a result of the heat exchangerelationship with the water. The refrigerant leaves the condenser and isdelivered to an evaporator. One type of evaporator or cooler is referredto as a chiller heat exchanger, commonly referred to as a directexpansion heat exchanger. The chiller heat exchanger places the liquidrefrigerant from the condenser into a heat exchange relationship with afluid, typically water, and undergoes a phase change to a refrigerantvapor as a result of the heat exchange relationship with the fluid,removing heat from the fluid, typically resulting in a reduction influid temperature. The cooled fluid then may be used for coolingapplications, including the cooling of buildings. The vapor refrigerantin the chiller heat exchanger exits the chiller heat exchanger andreturns to the compressor to complete the cycle. Chiller systems mayalso include multiple refrigerant circuits having independentrefrigerant loops. Refrigerant in the refrigerant loops circulatethrough one or more compressors, condensers and evaporators, withoutcombining refrigerant streams. Multiple refrigerant circuits may sharesingle components, such as evaporators. When multiple refrigerant loopsshare a single component, the refrigerant streams remain independent ofeach other, but exchange heat with the same fluid. In chiller heatexchangers, multiple sets of tubes may be used to maintain independentrefrigerant loops. The utilization of a single component in multiplecircuit systems allows for increased efficiency of the system andreduction in space required for the chiller system.

FIG. 1 shows a known chiller heat exchanger for use with an HVAC systemhaving flat plate headers 109 and 117. The chiller heat exchanger shownin FIG. 1 is a shell and tube heat exchanger having a shell 101, whichreceives a fluid, typically water, through shell inlet line 103. Thewater in the shell 101 enters into a heat exchange relationship withrefrigerant passing through tubes arranged within the shell 101. Thewater then exits the shell 101 through water outlet line 105. Liquidrefrigerant, typically from a condenser, is circulated to the chillerheat exchanger through refrigerant inlet line 107. Refrigerant inletline 107 delivers the liquid refrigerant to the first flat header 109.The first flat header 109 comprises a head plate 111 and a bafflechamber 113. The head plate 111 is a flat, relatively thick plate thatprovides containment for the refrigerant within the system. A gasketmust be placed between the head plate 111 and the baffle chamber 113 inorder to reduce leakage. The baffle chamber 113 contains one or morebaffles that direct the flow of refrigerant into a first set of tubes309 (see FIG. 3) that are arranged in the shell 101 and substantiallyprevents the direct flow of refrigerant between the inlet and outlet.The head plate 111 and the baffle chamber 113 are fastened to atubesheet 115 of shell 101 by fasteners 116. A second gasket must beplaced between the baffle chamber 113 and the tubesheet 115 in order toreduce leakage. The shell 101 includes a tubesheet 115 at each end ofthe shell 101 and provides openings into which refrigerant may pass anda flange to which the header may be attached. The return end of theshell 101 includes a second header 117. Like the first flat header 109,the second header 117 comprises a head plate 111 and baffle chamber 113.Also like the first flat header 109, the head plate 111 is a flat,relatively thick plate. Also like the first header 109, the second flatheader 117 requires at least two gaskets in order to reduce leakage.Center bolts 120 are also shown on the inlet/outlet and return heads.The liquid refrigerant from refrigerant inlet line 107 passes throughthe first flat header 109, enters the tubes arranged within the shell101 and travels to the second flat header 117. Heat transfer between therefrigerant and heat transfer fluid takes place within the shell 101 andgenerally results in a mixed phase refrigerant and liquid and vaporousrefrigerant. The refrigerant in the second flat header 117 then enters asecond set of tubes 311 (see FIG. 3), which flow back in a directiontoward the first flat header 109. The refrigerant continues to exchangeheat with the fluid in the shell 101 and reenters the first flat header109. The refrigerant then exits the first flat header 109 through outletline 119 substantially as a vapor. The baffle chamber 113 in each of thefirst flat header 109 and second flat header 117 may also include anarrangement that provides a number of passes of refrigerant across theshell that is greater than two.

FIG. 2 shows a chiller heat exchanger according to the presentinvention. FIG. 2 has substantially the same arrangement of shell 101,shell inlet line 103, water outlet line 105, tubesheet 115, refrigerantinlet line 107 and refrigerant outlet line 119, as shown and describedwith respect to FIG. 1. However, unlike FIG. 1, FIG. 2 includes a firstheader 201 and a second header 203 having a curved geometry, without theuse of a baffle chamber 113 and with a single gasket between firstheader 201 and second header 203 and tubesheets 115. The curved ordished heads are inexpensive and may be easily fabricated and eliminatethe need for center bolts. The gasket may be fabricated from anysuitable sealing device that provides sealing of the first and secondheaders 201 and 203 against the tubesheets 115. Suitable materialsinclude, but are not limited to neoprene or rubber. First header 201 andsecond header 203 are attached to shell 101 by fasteners 116. AlthoughFIG. 2 shows bolts fastening the first and second headers 201 and 203against the tubesheet, any suitable fastening means may be used,including welding, clamping or adhering the first and second headers 201and 203 to the tubesheet 115. The refrigerant inlet 108 and refrigerantoutlet 119 pass through the curved portion of first header 201 andprovides refrigerant to and takes refrigerant from the chiller heatexchanger. Although FIG. 2 only shows one refrigerant inlet 107 and onerefrigerant outlet 117, the chiller heat exchanger may include multipleinlets and outlets, corresponding to multiple circuits.

FIG. 3 shows a cutaway view of the heat exchanger according to thepresent invention, as shown in FIG. 2. Shell 101 contains a plurality oftubes 301, which fluidly connect inlet chamber 303 and outlet chamber305 to return chamber 307. The tubes 301 are divided into a first set oftubes 309 and a second set of tubes 311. Inlet chamber 303 receivesrefrigerant, typically liquid refrigerant, from refrigerant inlet line107. Refrigerant inlet line 107 includes a refrigerant diffuser 306 thatdiffuses the flow of refrigerant and distributes the refrigerant acrosstubes 301 of the first set of tubes 309. Although diffuser 306 has beenshown as a plate that directs flow substantially perpendicular to theflow into the chiller heat exchanger, any configuration of diffuser 306may be used so long as the flow of refrigerant is sufficiently diffusedto maintain efficient operation of the chiller heat exchanger. Therefrigerant in tubes 301 of the first set of tubes 309 flows from theinlet chamber 303 to the return chamber 307. Also, a flow restrictorplate 801 may be included to assure high velocity and enhancedperformance (see FIG. 8A). The location of the restrictor plate can beadjusted to achieve the desired refrigerant flow rate and achievedimproved efficiencies of operation.

As the refrigerant passes through the first set of tubes 309, heat isexchanged between the refrigerant in tubes 301 and fluid present in theshell 101. The fluid, typically water, in the shell flows into shellinlet 103, enters into a heat exchange relationship with the refrigerantin tubes 301, wherein the water is cooled, and exits through wateroutlet 105. The shell inlet 103 and shell outlet 105 may be positionedin any configuration along the length of the shell 101 that providesefficient operation of the chiller heat exchanger. The cooled waterleaving the chiller heat exchanger flows to a heat load, such as abuilding cooling system. Although the fluid in the shell has beendescribed as including water, any suitable heat exchange fluid may beused within the shell 101, including but not limited to brine or glycolsolutions. The heat transfer typically involves heat passing from thewater to the refrigerant and resulting in a phase change of therefrigerant from a liquid to a vapor. Refrigerant entering returnchamber 307 preferably includes a mixture of vapor and liquid. Therefrigerant in return header 307 is distributed across tubes 301 of thesecond set of tubes 311. The refrigerant from the return chamber 307flows in tubes 301 to outlet chamber 305. A baffle 313 attached to firstheader 201 separates the inlet chamber 303 from outlet chamber 305. Likein the first set of tubes 309, the refrigerant exchanges heat with thefluid in the shell 101 and continues to change from a liquid to a vapor.The refrigerant in outlet header 305 is preferably a vapor. Therefrigerant in outlet header 305 exits the chiller heat exchangerthrough outlet line 117. From the chiller heat exchanger refrigerantoutlet 117, the refrigerant continues to circulate through therefrigerant loop.

FIGS. 4A and 4B show cutaway views of first header 201 for attachment toa chiller heat exchanger for chiller systems having two refrigerantcircuits. Header 201 shown in FIGS. 4A and 4B includes refrigerant inlet107, refrigerant outlet 117, diffuser 306, and baffle 313, as shown anddescribed with respect to FIG. 3. FIG. 4A shows a side viewcross-section of first header 201. Header 201 includes a flange portion401 and a rounded wall portion 403. The rounded wall portion 403 definesinlet chamber 303 and outlet chamber 305 when attached to a tubesheet115 (see FIG. 3). Baffle 313 divides the first header 201 into inletchamber 303 and outlet chamber 305. FIGS. 4A and 4B show a tworefrigerant circuit system wherein one circuit corresponds to one of therefrigerant inlets 107 and one of the refrigerant outlets 117 and asecond circuit corresponds to the other refrigerant inlet 107 andrefrigerant outlet 117. FIG. 4B shows a cutaway front view of firstheader 201. FIG. 4B shows two refrigerant inlets 107 and two refrigerantoutlets 117. The refrigerant inlets 107 provide refrigerant to inletchambers 303. Inlet chambers 303 for each of the refrigerant circuitsare divided by circuit divider 405. Outlet chambers 305 for each of therefrigerant circuits are divided by circuit divider 405. Circuit divider405 extends from a first point 407 on the flange portion 401 to a secondpoint 409 on the flange portion 401 and extends circumferentially alongthe rounded wall portion 403 to form a seal that substantially preventsleakage of refrigerant between the two circuits.

FIGS. 5A and 5B show cutaway views of second header 203 for attachmentto the opposite end of a chiller heat exchanger as first header 201 byfasteners 116. FIG. 5A shows a side view cross-section of second header203. Like first header 201, second header 203 includes a flange portion401 and a rounded wall portion 403. The rounded wall portion 403 inFIGS. 5A and 5B defines return chamber 307 when attached to a tubesheet115 (see FIG. 3). FIG. 5B shows a cutaway front view of second header203. FIG. 5B shows two return chambers 307, each corresponding to one ofthe two refrigerant circuits. Return chambers 307 for each of therefrigerant circuits are divided by circuit divider 405. Circuit divider405 extends from a first point 407 on the flange portion 401 to a secondpoint 409 on the flange portion 401 and extends circumferentially alongthe rounded wall portion 403 to form a seal that substantially preventsleakage of refrigerant between the two circuits.

FIG. 6 shows a perspective view of first header 201 according to thepresent invention. FIG. 6 includes refrigerant inlets 107, refrigerantoutlets 117, flange portion 401, diffuser 306, baffle 313, and circuitdivider 405, as shown and described in FIGS. 3, 4A and 4B. The interiorspaces of inlet chamber 303 and outlet chamber 305 are shown. Inletchambers 303 and outlet chambers 305 are defined by the surfaces of thefirst header 201, rounded wall portion 403, the circuit divider 405,baffle 313 and tubesheet 115 (see FIG. 3) when first header 201 isattached to tubesheet 115 by fasteners 116. A gasket 601 is disposedadjacent to the flange portion 401, circuit divider 405 and baffle 313in order to provide a seal when the first header is fastened totubesheet 115. The refrigerant inlets 107 and refrigerant outlets 117extend into the interior spaces of inlets chamber 303 and outletchambers 305. The extension of the refrigerant inlets 107 andrefrigerant outlets 117 permit refrigerant to flow into or from thetubes 301 with a desirable flow profile and maintain efficient operationof the heat exchanger.

FIG. 7 shows a perspective view of second header 203 according to thepresent invention. FIG. 7 includes flange portion 401, and circuitdivider 405, as shown and described in FIGS. 3, 5A and 5B. The interiorspace of return chamber 307 is shown. Return chamber 307 is formed whensecond header 203 is fastened to tubesheet 115 (see FIG. 3) by fasteners116. The return chamber defined by the rounded wall portion 403, circuitdivider 405 and tubesheet 115 when the second header 203 is attached totubesheet 115. The geometry of return chamber 307, including the roundedwall portion 403, provides efficient flow of refrigerant through theheat exchanger wherein the refrigerant maintains a high velocity.

FIGS. 8A and 8B show a cutaway view of an alternate embodiment accordingto the present invention. FIG. 8A shows a cutaway side view of firstheader 201 having inlet chamber 303, and outlet chamber 305 as shown anddescribed with respect to FIG. 4A. However, FIG. 8A further includes arestrictor plate 801 that reduces the volume of the chambers 303 and305. Restrictor plate 801 is preferably attached to the rounded wallportion 403 and sealed to provide a predetermined volume within thechambers. Although FIG. 8A shows the restrictor plate 801 arrangedvertically within the header across refrigerant inlet 107 andrefrigerant outlet 117, restrictor plate 801 may be arranged in anysuitable configuration that provides control of the volume within theinlet and outlet chambers 303 and 305. Restrictor plate 801 providesadditional control of the velocity of the refrigerant through thechiller heat exchanger. In addition, the restrictor plate 801 providesthe refrigerant inlet 107 and refrigerant outlet 117 with greaterstability from the additional attachment point to the first header 201.The restrictor plate 801 also provides a surface to which the diffuser306 may be attached, providing for easier assembly of the first header201. FIG. 8B shows a cutaway front view of first header 201 having inletchamber 303, and outlet chamber 305 as shown and described with respectto FIG. 4B. FIG. 8B includes a restrictor plate 801 reducing the volumeof the chambers 303 and 305. As shown in FIG. 8B, the restrictor plate801 is circumferentially attached to wall portion 403. Although therestrictor plate is shown as a substantially flat plate, the restrictorplate may be any geometry that reduces the volume in inlet and outletchambers 303 and 305. For example, the restrictor plate 801 may also bea curved portion having a smaller radius of curvature than the first andsecond headers 201 and 203, forming a chamber including at least onecurved surface. Further, the restrictor plates 801 may be present in anycombination of chambers, including one or more of the inlet chamber 303,outlet chamber 305, and return chamber 307. In addition, refrigerantinlets 107 and refrigerant outlets 117 extend through the restrictorplate 801 and are likewise attached to restrictor plate 801. The circuitdivider 405 and baffle 313 are attached to and extend from therestrictor plate 801 to an extent that allows a seal when first header201 is attached to a tubesheet 115 (see FIG. 3). Although FIGS. 8A and8B show the baffle and circuit divider 405 extending from the restrictorplate 801, the baffle 313 and circuit divider may also extend throughthe restrictor plate 801 to the rounded wall portion 403.

FIGS. 9A and 9B show second header 203 according to an alternateembodiment of the invention. FIG. 9A shows a cutaway side view of secondheader 203 having return chamber 307, as shown and described withrespect to FIG. 5A. FIG. 9A further includes a restrictor plate 801 thatreduces the volume of the return chamber 307. FIG. 9B shows a cutawayfront view of second header 203 having return chamber 307, as shown anddescribed with respect to FIG. 5B. The circuit divider 405 shown inFIGS. 9A and 9B is attached to and extends perpendicularly from therestrictor plate 801 to an extent that allows a seal when second header203 is attached to a tubesheet 115 (see FIG. 3).

FIG. 10 shows a perspective view of first header 201 according to analternate embodiment of the invention. FIG. 10 shows the arrangement ofFIG. 6 further comprising restrictor plate 801. As shown and describewith respect to FIGS. 8A and 8B, restrictor plate 801 iscircumferentially attached to the wall portion 403, reducing the volumeof inlet chambers 303 and outlet chambers 305 when the first header 202is attached to tubesheet 115. The interior spaces of inlet chamber 303and outlet chamber 305 are shown. Inlet chambers 303 and outlet chambers305 are defined by the surfaces of the first header 201, rounded wallportion 403, circuit divider 405, baffle 313, tubesheet 115 (see FIG. 3)and restrictor plate 801 when first header 201 is attached to tubesheet115 by fasteners 116. Like shown in FIG. 6, gasket 601 is disposedadjacent to the flange portion 401, circuit divider 405 and baffle 313in order to provide a seal when the first header is fastened totubesheet 115. The refrigerant inlets 107 and refrigerant outlets 117extend into the interior spaces of inlets chamber 303 and outletchambers 305 and are attached to the restrictor plate 801. The extensionof the refrigerant inlets 107 and refrigerant outlets 117 permitrefrigerant to flow into the tubes 301 with a desirable flow profile andmaintain efficient operation of the heat exchanger.

FIG. 11 shows a perspective view of second header 203 according to analternate embodiment of the invention. FIG. 11 shows the arrangement ofFIG. 7 further comprising restrictor plate 801. As shown and describewith respect to FIGS. 9A and 9B, restrictor plate 801 iscircumferentially attached to the wall portion 403, reducing the volumeof return chamber 307 when the first header 202 is attached to tubesheet115. The interior space of return chamber 307 is shown. Return chamber307 is formed when second header 203 is fastened to tubesheet 115 (seeFIG. 3) by fasteners 116. The return chamber defined by the rounded wallportion 403, circuit divider 405, tubesheet 115 and restrictor plate 801when the second header 203 is attached to tubesheet 115. The geometry ofreturn chamber 307, including the rounded wall portion 403, providesefficient flow of refrigerant through the heat exchanger wherein therefrigerant maintains a high velocity.

Although the invention has been shown and described with respect to tworefrigerant circuits, any number of refrigerant circuits may be used.For example, two circuit dividers 405 may be attached to the roundedwall portion 403 to accommodate three circuits. Likewise, although theinvention has been shown and described with respect to a two-passsystem, baffles 313 and tubes 301 may be arranged into three or morepasses.

While the invention has been described with reference to a preferredembodiment, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

1. A header assembly for a heat exchanger comprising: a containmentbody, the containment body comprising a rounded wall portion forming aninterior cavity; a flange portion attached to the containment body andbeing configured to fasten the header assembly to the heat exchanger; aplurality of refrigerant passageways, each passageway extending throughan opening in the containment body and in fluid communication with theinterior cavity; the interior cavity being divided into a plurality ofsub-cavities, the sub-cavities being further divided into a plurality ofchambers; the plurality of passageways including an inlet connection andan outlet connection for a plurality of refrigerant circuits, and eachpassageway is disposed in a corresponding chamber of the plurality ofchambers; and wherein the header assembly further includes a restrictorplate attached to the containment body and disposed within at least oneof the plurality of chambers arranged to reduce the effective volume ofthe at least one of the plurality of chambers.
 2. The header assembly ofclaim 1, wherein the baffles are adapted to deliver refrigerant to tubesof the heat exchanger when the header is fastened to the heat exchanger.3. The header assembly of claim 1, wherein the plurality of chambersincludes an inlet chamber and an outlet chamber for each refrigerantcircuit.
 4. The header assembly of claim 3, wherein the header assemblyincludes two inlet chambers and two outlet chambers, wherein the headeris capable of receiving refrigerant from two refrigerant circuits. 5.The header assembly of claim 3, wherein the header assembly includes atleast three inlet chambers and at least three outlet chambers, whereinthe header is capable of receiving refrigerant from at least threerefrigerant circuits
 6. The header assembly of claim 1, wherein theheader assembly further includes a gasket arranged and disposed to sealthe chambers of the containment body against the heat exchanger in orderto substantially prevent leaks of refrigerant to the atmosphere andbetween the plurality of chambers when the header assembly is attachedto a heat exchanger.
 7. The header assembly of claim 1, wherein theinlet connection includes a diffuser to diffuse the flow of refrigerantinto the heat exchanger.
 8. A header assembly for attachment to a heatexchanger comprising: a containment body, the containment bodycomprising a rounded wall portion forming an interior cavity; a flangeportion attached to the containment body and being configured to fastenthe header assembly to the heat exchanger; a gasket arranged anddisposed to seal the containment body against the heat exchanger inorder to substantially prevent leaks of fluid to the atmosphere andamong the plurality of chambers when the header assembly is attached tothe heat exchanger; wherein the cavities are divided into a plurality ofchambers and the plurality of chambers include a return chamber for eachrefrigerant circuit; and wherein the header assembly further includes arestrictor plate attached to the containment body and disposed within atleast one of the plurality of chambers arranged to reduce the effectivevolume of the at least one of the plurality of chambers.
 9. The headerassembly of claim 8, wherein the header assembly includes two returnchambers, corresponding to two refrigerant circuits.
 10. The headerassembly of claim 8, wherein the header assembly includes returnchambers, corresponding to three refrigerant circuits.
 11. A heatexchanger comprising: a shell for containing heat transfer fluid havinga first end and a second end; a plurality of tubes for containingrefrigerant arranged and disposed within the shell, the plurality oftubes including a first set of tubes and a second set of tubes, a firstheader assembly detachably fastened to the first end, the first headerassembly comprising: a containment body, the containment body comprisinga rounded wall portion forming an interior cavity; a flange portionattached to the containment body and being configured to fasten thefirst header assembly to the first end; a plurality of refrigerantpassageways, each passageway extending through an opening in thecontainment body and in fluid communication with the interior cavity;the interior cavity being divided into a plurality of sub-cavities, thesub-cavities being further divided into a plurality of chambers; andwherein the plurality of passageways includes an inlet connection and anoutlet connection for a plurality of refrigerant circuits, and eachpassageway is disposed in a corresponding chamber of the plurality ofchambers; a first gasket disposed between the first header and the firstend substantially preventing leakage of refrigerant from the firstheader assembly; a second header assembly detachably fastened to thesecond end, the second header assembly comprising: a containment body,the containment body comprising a rounded wall portion forming aninterior cavity; a flange portion attached to the containment body andbeing configured to fasten the second header assembly to the second end;a gasket arranged and disposed to seal the chambers of the containmentbody against the heat exchanger in order to substantially prevent leaksof refrigerant to the atmosphere and between the plurality of chamberswhen the second header assembly is attached to the second end; andwherein the cavities are divided into a plurality of chambers and theplurality of chambers include a return chamber for each refrigerantcircuit; wherein one or both of the first header assembly or the secondheader assembly further includes a restrictor plate attached to thecontainment body and disposed within at least one of the plurality ofchambers arranged to reduce the effective volume of the at least one ofthe plurality of chambers; and a second gasket disposed between thesecond header and the second end substantially preventing leakage ofrefrigerant from the second header assembly.
 12. The heat exchanger ofclaim 11, further including a gasket disposed between the first headerassembly and the first end and a gasket disposed between the secondheader assembly and the second end to seal the chambers of the firstcontainment body and the second containment body against the heatexchanger in order to substantially prevent leaks of refrigerant to theatmosphere and between the plurality of chambers.
 13. The heat exchangerof claim 11, wherein the inlet connection includes a diffuser to diffusethe flow of refrigerant into the heat exchanger.